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Hemoglobin A1c (HbA1c) – Glycated Hemoglobin

Published: August 9, 2026Updated: August 16, 2026

This test measures the percentage of hemoglobin in your blood that has been linked to sugar (glucose), reflecting your average blood sugar levels over the past 2–3 months.

Quick summary

["HbA1c helps doctors track diabetes control and long-term blood sugar trends."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
60866-1
Short code
O2 VFr/PPres Away adap
Synonyms
O2 VFr/PPres Away adap
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Matters for Your Health

HbA1c is a key indicator of how well your body manages blood sugar, especially for people with diabetes or prediabetes. It provides a snapshot of your average glucose levels over time, which can help prevent complications like nerve damage, kidney disease, or heart problems.

How the Test Works

Blood is drawn from a vein, usually in your arm. The sample is processed to measure the proportion of hemoglobin molecules that have sugar molecules attached. This test doesn’t require fasting.

What to Expect Before the Test

No special preparation is needed, but let your doctor or lab know if you’re taking blood thinners or have a history of bleeding disorders. Avoid smoking or caffeine for 30 minutes before the test if possible.

What the Results Mean

Results are typically reported as a percentage (e.g., 5.5%). Higher percentages suggest poorer blood sugar control, while lower percentages may indicate better control. Your doctor will interpret results based on your medical history and goals.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

HbA1c

Frequently asked questions

What does an abnormal HbA1c result mean?
An HbA1c result above the target range (often 7% or lower for diabetes) may indicate poor blood sugar management and could require adjustments to medication, diet, or exercise. A result below the target may prompt further evaluation to avoid hypoglycemia (low blood sugar).
Can HbA1c be affected by other health conditions?
Yes, conditions like anemia, kidney disease, or certain medications (e.g., some blood pressure drugs) can influence HbA1c levels. Your doctor will consider these factors when interpreting your result.
How often should I get an HbA1c test?
Typically, people with diabetes check HbA1c every 3–6 months. Your doctor may recommend more frequent testing if your blood sugar is unstable or if you’re adjusting treatments. Regular monitoring helps prevent long-term complications.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy